Support cushion



FIG. 1 is a front perspective view of a support cushion, showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a right side elevation view thereof; the left side elevation view being a mirror image thereof;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a support cushion, as shown and described. 